CN108462350B

CN108462350B - Electric tool

Info

Publication number: CN108462350B
Application number: CN201810123389.7A
Authority: CN
Inventors: 多安·托安·潘; 大村翔洋; 长滨达也
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2017-02-20
Filing date: 2018-02-07
Publication date: 2021-03-19
Anticipated expiration: 2038-02-07
Also published as: US10886816B2; US20180241281A1; JP2018137843A; DE102018103644A1; CN108462350A; JP6883442B2

Abstract

The invention provides an electric tool. The hammer drill comprises a main body casing, a brushless motor (4) and a bearing (22), wherein the brushless motor (4) comprises: a stator (7); a rotor (8) having a rotating shaft (9); and a sensor circuit board (54) that is fixed to the stator (7), is penetrated by the rotating shaft (9), and is mounted with a magnetic sensor (77) that detects rotation of the rotor (8), wherein the bearing (22) is held by the main body case, and supports the rotating shaft (9), and wherein the bearing (22) of the rotating shaft (9) and the magnetic sensor (77) of the sensor circuit board (54) overlap in the axial direction of the rotating shaft (9). Accordingly, the bearing of the rotating shaft can be set to be large even if the brushless motor is provided with the sensor circuit board.

Description

Electric tool

Technical Field

The present invention relates to an electric power tool such as a hammer drill (hammer drill) using a brushless motor (brushless motor) as a drive source.

Background

As an electric tool such as a hammer drill, an electric tool using a brushless motor as a driving source is known. As disclosed in patent document 1, this brushless motor includes: a stator (stator) having a winding (coil); a rotor having a rotation axis; and a sensor circuit board which is mounted on the stator and on which 3 magnetic sensors (rotation detecting elements such as hall elements) are provided, the magnetic sensors detecting positions of permanent magnets provided on the rotor and outputting detection signals. The controller obtains a detection signal from the magnetic sensor to acquire a rotational position of the rotor, and sequentially energizes the windings of the stator via the switching elements to rotate the rotor.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-7068

Disclosure of Invention

In the brushless motor of the electric power tool, the rotor is assembled in a state where the sensor circuit board is assembled to the stator, and therefore, a through hole through which the rotation shaft of the rotor and the bearing thereof can be inserted is formed in the center of the sensor circuit board and inside the magnetic sensor. Therefore, the bearing having a diameter larger than that of the through hole of the sensor circuit board cannot be provided on the rotary shaft, which may result in a reduction in the life of the bearing and a reduction in the durability of the electric power tool itself.

Accordingly, an object of the present invention is to provide an electric power tool having a large diameter of a bearing of a rotating shaft and excellent durability even if a sensor circuit board is provided on a brushless motor.

In order to achieve the above object, the invention according to claim 1 is an electric power tool including a housing, a brushless motor, and a bearing,

the brushless motor has: a stator; a rotor having a rotation axis; and a sensor circuit board that is fixed to the stator, is penetrated by the rotating shaft, and is mounted with a rotation detection element that detects rotation of the rotor;

the bearing is held by the housing and supports the rotating shaft,

the bearing of the rotating shaft and the rotation detecting element of the sensor circuit board overlap in the axial direction of the rotating shaft.

The invention described in claim 2 is: on the basis of the technical scheme 1, the sensor circuit board is provided with a through hole and an avoidance hole, wherein the through hole is penetrated by the rotating shaft and is provided with a rotation detection element around the periphery of the through hole; the avoidance hole is communicated with the through hole and is formed to have a diameter (caliber) larger than that of the through hole, the bearing can pass through the avoidance hole,

in a fixed state in which the sensor circuit board is fixed to the stator, the bearing overlaps the through hole and the rotation detecting element.

In order to achieve the above object, the invention according to claim 3 is an electric power tool including a housing, a brushless motor, and a bearing, wherein,

the bearing is held by the housing and supports the rotating shaft,

the sensor circuit board has a hole portion formed with a radius larger than a distance from a center of the rotation shaft to the rotation detecting element.

In order to achieve the above object, the invention according to claim 4 is an electric power tool including a housing, a brushless motor, and a bearing, wherein,

the bearing is held by the housing and supports the rotating shaft;

the sensor circuit board is formed to have a size such that an angle (rotation angle) around the rotation axis reaches 180 degrees or more while retaining at least a circumferential gap through which the rotation axis can pass in the radial direction, and a fixing portion to be fixed to the stator is provided in a region of 180 degrees or more.

According to the present invention, the diameter of the bearing of the rotating shaft is large even if the brushless motor has the sensor circuit board. Therefore, the life of the bearing can be kept long, and the durability can be improved.

Drawings

FIG. 1 is a central longitudinal cross-sectional view of the hammer drill.

Fig. 2 is an exploded perspective view of the brushless motor.

Fig. 3 is a front view of the stator.

Fig. 4 is an explanatory view of the sensor circuit board, where (a) shows a top view (lower insulator side), and (B) shows a bottom view.

Fig. 5 is an explanatory view showing a state before the sensor circuit board is mounted, where (a) shows a perspective view, and (B) shows a side view.

Fig. 6 is an explanatory view showing a state before the sensor circuit board is positioned, (a) shows a perspective view, (B) shows a side view, and (C) shows a front view.

Fig. 7 is an explanatory view showing a positioning state of the sensor circuit board, (a) shows a perspective view, (B) shows a side view, and (C) shows a front view.

Fig. 8 is an explanatory view showing a state before the sensor circuit board is mounted in a modification, (a) shows a front view, and (B) shows a perspective view.

Fig. 9 is an explanatory view showing a positioning state of a sensor circuit board according to a modification, (a) shows a front view, and (B) shows a perspective view.

Description of the reference numerals

1: a hammer drill; 2: a main body case; 3: a front housing; 4: a brushless motor; 6: an output section; 7: a stator; 8: a rotor; 9: a rotating shaft; 12: a controller; 19: an intermediate shaft; 20: a tool holder; 21. 22, 32, 33: a bearing; 37: a piston cylinder; 39: a striking member; 50: a stator core; 51: an upper insulator; 52: a lower insulator; 53: a winding; 54. 54A: a sensor circuit board; 55: an annular portion; 56: a connecting sheet; 57: a screw post; 60A to 60C: a solder terminal (fusing terminal); 65: a circular portion; 66: a screw fixing piece (fixing portion); 67. 71: through holes; 68: positioning plates; 70: an extension portion (fixed portion); 73: a long hole; 74: a penetrating portion (through hole); 75: avoidance portions (avoidance holes, hole portions); 76: a square hole portion; 77: a magnetic sensor (rotation detecting element); 78: a conductive pattern; 80: a rotor core; 84: a control circuit board; 87: a screw; 90: a through hole; 91: a gap.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a longitudinal sectional view of a hammer drill as an example of an electric power tool. The hammer drill 1 includes: a main body case 2 which houses the brushless motor 4 and the like and is formed by assembling a pair of right and left half cases with a plurality of

screws

5 and 5 …; a front case 3 in a tapered cylindrical shape, which is assembled with screws not shown from the front to the upper front of the main body case 2, and houses the output unit 6.

The brushless motor 4 is an inner rotor type motor having a cylindrical stator 7 and a rotor 8 penetrating the stator 7, and is held in a posture in which a rotary shaft 9 of the rotor 8 is directed upward and inclined obliquely rearward. A battery mounting portion 10 is formed on the main body casing 2 at the rear of the brushless motor 4, the battery mounting portion 10 is used for mounting 2 battery packs 11, 11 as a power source, and a controller 12 extending in the front-rear direction and

terminal blocks

13, 13 electrically connecting the battery packs 11 below the controller 12 are provided in the battery mounting portion 10. A handle 14 is formed vertically above the battery mounting portion 10, and a switch 15 for projecting a trigger 16 forward and a forward/reverse rotation switching lever 17 of a motor are housed in the handle 14.

The output section 6 is housed in a front side of an inner housing 18 provided at a rear portion inside the front housing 3, and includes a front-rear direction intermediate shaft 19 and a cylindrical tool holder 20, and the cylindrical tool holder 20 extends in the front-rear direction above the intermediate shaft 19. The rotary shaft 9 of the brushless motor 4 is held by an upper bearing 21 and a lower bearing 22, the upper end of which protrudes into the front housing 3, the upper bearing 21 being held by the inner housing 18, and the lower bearing 22 being held by the main body housing 2, and a 1 st gear 23 provided at the upper end of which is engaged with a 2 nd gear 24 provided at the rear portion of the intermediate shaft 19. The rear end shaft of the intermediate shaft 19 is supported by the inner housing 18 and the front end shaft is supported by the front inner surface of the front housing 3 via

bearings

25 and 25, respectively.

A hub sleeve (boss sleeve)26 and a 3 rd gear 29 forward of the hub sleeve 26 are rotatably fitted around the intermediate shaft 19 in front of the 2 nd gear 24, wherein the hub sleeve 26 is fitted around an arm portion 28 via a slant bearing (shock bearing)27 whose axis is inclined. A pair of front and

rear clutches

30, 31 are spline-coupled to the intermediate shaft 19 between the hub sleeve 26 and the 3 rd gear 29. The

clutches

30 and 31 can be switched to a position where only the rear clutch 31 is engaged with the hub sleeve 26, a position where only the front clutch 30 is engaged with the 3 rd gear 29, and a position where the clutch 31 is engaged with the hub sleeve 26 and the clutch 30 is engaged with the 3 rd gear 29 by operating a switching lever, not shown, provided on the side surface of the front housing 3.

The tool holder 20 is rotatably supported at the front of the inner housing 18 by a bearing 32 held at the middle portion of the front housing 3 and a bearing 33 held at the front end portion of the front housing 3, and a 4 th gear 34 provided at the middle portion is engaged with the 3 rd gear 29 of the intermediate shaft 19. The 4 th gear 34 is engaged with the retainer ring 35 fixed to the tool holder 20 at the front thereof in the rotational direction, and is pressed from the rear by the coil spring 36, whereby the 4 th gear 34 is integrated with the tool holder 20 in the rotational direction. That is, the following torque limiter (torque limiter) is formed: when the torque applied to the tool holder 20 increases, the 4 th gear 34 retreats from the carrier ring 35 against the biasing force of the coil spring 36 and separates from the tool holder 20.

A piston cylinder 37(piston cylinder) having a rear end connected to the arm portion 28 is housed in a rear portion of the tool holder 20 so as to be reciprocatingly movable, and a striking element 39 is housed inside the piston cylinder 37 so as to be reciprocatingly movable through an air chamber 38. An intermediate member 40 that abuts against a tip tool, not shown, such as a drill attached to the tip is provided on the tool holder 20 in front of the striker 39, and a holding member 41 is provided around the intermediate member 40, and the intermediate member 40 is held at the advanced position by the holding member 41 in a state where the tip tool is not attached, so that the striker 39 is prevented from being emptied. Reference numeral 42 denotes a coil spring which is provided between the inner housing 18 and the piston cylinder 37 and which biases the piston cylinder 37 to the advanced position in the drill mode to prevent an unnecessary striking operation from occurring, reference numeral 43 denotes an operation sleeve for performing an operation of attaching and detaching the tip tool to and from the tool holder 20, and reference numeral 44 denotes a Lamp (LED) which is provided in a diagonally upward and forward direction toward the main body housing 2 in front of the brushless motor 4 and irradiates the front of the tip tool.

As shown in fig. 2 and 3, in brushless motor 4, stator 7 includes: a cylindrical stator core 50(stator core) formed of a plurality of laminated steel plates; an upper insulator 51 and a lower insulator 52 provided on upper and lower end surfaces of the stator core 50 in the axial direction, respectively; and 6

windings

53 and 53 … wound inside the stator core 50 with the upper insulator 51 and the lower insulator 52 interposed therebetween. A sensor circuit board 54 described later is fixed to the lower insulator 52.

The lower insulator 52 has: a resin annular portion 55 having an outer diameter substantially equal to the outer diameter of the stator core 50; and a connecting piece 56 protruding from the annular portion 55 in the radial direction toward the controller 12. On the lower surface of the ring-shaped

portion

55, 3 screw bosses (screw holes) 57, 57 … are provided at equal intervals in the circumferential direction in a manner of being located at the vertices of a regular triangle, the 3

screw bosses

57, 57 … are used for fixing the sensor circuit board 54 by screws, and 2

positioning bosses

58, 58 and 3 holding

portions

59, 59 … are provided between the screw bosses 57, wherein the 2

positioning bosses

58, 58 are used for positioning the sensor circuit board 54; the 3

holding portions

59 and 59 … hold the clamping portions 61 of the solder terminals (fusing terminals) 60A to 60C described later.

On the lower surface of the

lower insulator

52, 3 solder terminals 60A to 60C for connecting a lead wire as a power supply line to the windings 53 of the three phases are provided. The left and

right solder terminals

60A, 60B have, at one end, a clamping portion 61 for clamping and soldering the winding wire of the winding 53, the clamping portion 61 is a band-shaped metal member held by the front left and right holding

portions

59, 59 and extending in an arc shape along the annular portion 55, and the other end extends along the left and right outer sides on the lower surface of the connecting piece 56 and is bent and locked to the connecting piece 56. The central solder terminal 60C also has a clamping portion 61 at one end thereof for clamping and soldering the winding wire, the clamping portion 61 being a band-shaped metal member held by the holding portion 59 at the rear center and extending along the center portion on the lower surface of the connecting piece 56, and the other end thereof being bent and locked to the connecting piece 56.

Partition ribs

62, 62 are erected on the lower surface of the connecting piece 56, the

partition ribs

62, 62 partition between the solder terminals 60A to 60C, and nuts, not shown, corresponding to the solder terminals 60A to 60C are embedded in the respective portions partitioned by the partition ribs 62. A terminal unit 63 in the shape of japanese katakana "コ" in side view is attached to the connecting piece 56 in a clamped manner from the rear, and lead wires routed from the controller 12 and corresponding to the solder terminals 60A to 60C are soldered to the terminal unit 63. In this state, the terminal unit 63 and the connecting piece 56 are coupled and electrically connected by

screws

64 and 64 … that penetrate the solder terminals 60A to 60C and are screwed into nuts.

The sensor circuit board 54 is an oblong shape extending from the inside of the annular portion 55 of the lower insulator 52 to the connecting piece 56 in the front-rear direction, and has a circular portion 65 formed at the front end side thereof to be smaller than the annular portion 55 by one turn, and a

screw fixing piece

66 and 2

positioning pieces

68, 68 formed radially at the outer periphery thereof, wherein the screw fixing piece 66 has a through hole 67 corresponding to the screw post 57 at the center of the front side; the 2

positioning pieces

68 and 68 are respectively provided with small holes 69 corresponding to the left and

right positioning bosses

58 and 58. Further, protruding

portions

70, 70 are formed on the left and right sides of the central portion of the sensor circuit board 54, and the protruding

portions

70, 70 have through holes 71 corresponding to the left and

right screw bosses

57, 57. The rear end of the sensor circuit board 54 is a trapezoidal portion 72 extending rearward below the connecting piece 56. The mark 71a is a small hole for discriminating the left and right directions.

A long hole 73 extending in the longitudinal direction is formed in the center of the sensor circuit board 54. The long hole 73 is formed by continuously forming a penetrating portion 74, a relief portion 75, and a square hole portion 76, wherein the penetrating portion 74 is formed in a circular shape concentric with the circular portion 65, is capable of penetrating the rotary shaft 9 of the rotor 8, and has a diameter smaller than that of the bearing 22 provided on the lower side of the rotary shaft 9; the escape portion 75 communicates with the rear side of the penetrating portion 74 and is formed in a circular shape having a diameter larger than that of the bearing 22; the square hole 76 communicates with the rear side of the escape portion 75, and has a square shape having a width smaller than that of the escape portion 75.

As shown in fig. 4a, 3 magnetic sensors (hall elements in this case) 77 and 77 … that detect the positions of the

permanent magnets

81 and 81 … provided on the rotor 8 and output rotation detection signals are mounted concentrically around the outer periphery of the through portion 74 on the upper surface (surface on the lower insulator 52 side) of the sensor circuit board 54, and

conductive patterns

78 and 78 … in which the 3 magnetic sensors 77 are connected in parallel are formed from the circular portion 65 to the trapezoidal portion 72 on both the front and rear surfaces and on the outer side of the long hole 73. On the lower surface side of the sensor circuit board 54,

connection portions

79, 79 … are formed at the trapezoidal portion 72, and the

connection portions

79, 79 … are connected to the respective conductive patterns 78 for connecting 5 wires (2 connection portions 79 on the outer sides of both sides are used for power supply, and 3 connection portions 79 in the middle are used for output signals). Here, as shown in fig. 4a, the radius R of the relief portion 75 is larger than the radial distance D from the center O of the through portion 74 (the center of the rotary shaft 9 of the through portion 74) to the magnetic sensor 77.

The rotor 8 has: a rotating shaft 9 located at the axial center; a substantially cylindrical rotor core 80 disposed around the rotating shaft 9 and formed by stacking a plurality of steel plates; and 4 plate-like

permanent magnets

81 and 81 … fixed inside rotor core 80. A centrifugal fan 82 is mounted between the stator 7 on the rotary shaft 9 and the upper bearing 21. A plurality of exhaust ports (not shown) are formed in the main body casing 2 outside the centrifugal fan 82, and a plurality of

intake ports

83 and 83 … (fig. 1) are arranged linearly in the front-rear direction on the side surface of the main body casing 2 below the brushless motor 4. The suction port 83 is also formed outside the controller 12.

The controller 12 is configured by housing a control circuit board 84 in a case 85 made of resin and having a flat rectangular box shape, and is held in the front-rear direction by holding

ribs

86, 86 shaped like japanese katakana "コ" protruding toward the inner surface of the main body case 2 on the terminal block 13, wherein the control circuit board 84 is mounted with a microcomputer, a capacitor, a switching element for controlling the energization of the winding 53 of the stator 7, and the like.

When assembling the brushless motor 4, as shown in fig. 5, first, the rotor 8 to which the

bearings

21 and 22 and the centrifugal fan 82 are attached is inserted from the upper insulator 51 side through the stator 7 before the sensor circuit board 54 is attached, with the bearing 22 as a first step.

Next, as shown in fig. 6, the surface of the sensor circuit board 54 on the magnetic sensor 77 side is directed toward the lower insulator 52, and the rotary shaft 9 is inserted through the escape portion 75. Here, since the diameter (bore) of the escape portion 75 is larger than the diameter of the bearing 22, the rotary shaft 9 can pass through the escape portion 75 without hindrance even if the bearing 22 is present.

Then, as shown in fig. 7, the sensor circuit board 54 is slid toward the connecting piece 56, the screw fixing piece 66 and the through

holes

67, 71 of the

extension portions

70, 70 are aligned with the screw posts 57, and the

positioning bosses

58, 58 are fitted into the

small holes

69, 69 of the positioning pieces 68, respectively. Accordingly, the rotary shaft 9 is relatively moved to a position concentric with the through portion 74, and the sensor circuit board 54 is positioned at the mounting position. At this time, the holding portion 59 on the connecting piece 56 side and the clamping portion 61 of the solder terminal 60C protrude into the square hole portion 76 of the long hole 73, and therefore do not interfere with the sensor circuit board 54.

Finally, the screw fixing piece 66 and the

extension portions

70 and 70 are fixed to the respective screw posts 57 by

screws

87 and 87 … (fig. 2), whereby the brushless motor 4 can be assembled in the main body case 2 after the assembly is completed.

In the brushless motor 4, the bearing 22 having a larger diameter than the diameter of the through portion 74 is used, and as shown in fig. 4 (a), the radius of the escape portion 75 through which the bearing 22 passes is larger than the radial distance D from the center O of the rotating shaft 9 passing through the through portion 74 to the magnetic sensor 77. By setting the diameter of the bearing 22 to be large in this way, as shown in fig. 7 (C), the magnetic sensor 77 located outside the through portion 74 and the bearing 22 overlap each other in the axial direction of the rotary shaft 9.

In the hammer drill 1 configured as described above, when the trigger 16 is pushed and the switch 15 is turned on, the control circuit board 84 of the controller 12 supplies the power of the battery packs 11 and 11 to the brushless motor 4 to drive the brushless motor 4. That is, the microcomputer of the control circuit board 84 obtains the rotation detection signal indicating the position of the permanent magnet 81 of the rotor 8 output from the magnetic sensor 77 of the sensor circuit board 54 to acquire the rotation state of the rotor 8, controls ON/OFF of each switching element in accordance with the acquired rotation state, and rotates the rotor 8 by sequentially passing a current through each winding 53 of the stator 7. Therefore, the rotation shaft 9 rotates to rotate the intermediate shaft 19 via the 1 st gear 23 and the 2 nd gear 24.

At this time, when only the rear clutch 31 is engaged with the hub sleeve 26, the rotation of the intermediate shaft 19 is transmitted to the hub sleeve 26, and is converted into the forward and backward swinging of the arm portion 28 by the angular bearing 27. Therefore, the piston cylinder 37 reciprocates together with the arm portion 28, and the air chamber 38 causes the striker 39 to be interlocked, thereby providing a hammering mode in which a hammering is transmitted to the tip tool through the intermediate member 40.

In addition, when only the front clutch 30 is engaged with the 3 rd gear 29, the rotation of the intermediate shaft 19 is transmitted to the 3 rd gear 29, and the tool holder 20 is rotated by the 4 th gear 34. Therefore, the tip tool rotates together with the tool holder 20 in the drilling mode.

When the

clutches

30 and 31 are engaged with the hub sleeve 26 and the 3 rd gear 29, the hammer drill mode is established in which the hammering and rotation are transmitted to the tip end tool.

When centrifugal fan 82 rotates with the rotation of rotary shaft 9, outside air is sucked through air inlet 83 below brushless motor 4 and an air inlet outside controller 12. The air flow from the air inlet 83 rises in the main body casing 2, passes between the stator 7 and the rotor 8, cools the brushless motor 4, and is then discharged from the exhaust port. The air flow from the air inlet on the controller 12 side passes through the controller 12 and flows forward along the housing 85, thereby cooling the switching elements and the like of the control circuit board 84, and then merges with the air flow on the brushless motor 4 side and is discharged from the exhaust port.

Here, in brushless motor 4, sensor circuit board 54 has circular portion 65 with a diameter smaller than that of annular portion 55 of lower insulator 52 and has large long hole 73 in the center, and therefore, the air flow entering from the lower insulator 52 side can pass through the inside and outside of sensor circuit board 54 and smoothly pass between stator 7 and rotor 8, whereby a high cooling effect can be maintained even if sensor circuit board 54 long in the front-rear direction is employed.

In this way, according to the hammer drill 1 of the above-described aspect, the bearing 22 of the rotary shaft 9 and the magnetic sensor 77 of the sensor circuit board 54 overlap in the axial direction of the rotary shaft 9, and therefore, even if the sensor circuit board 54 is provided on the brushless motor 4, the diameter of the bearing 22 of the rotary shaft 9 is relatively large. Therefore, the durability can be improved while the life of the bearing 22 is kept long.

In particular, the sensor circuit board 54 has a through portion 74 and a relief portion 75, wherein the through portion 74 is penetrated by the rotating shaft 9 and a magnetic sensor 77 is disposed around the outer periphery thereof; the escape portion 75 is formed to communicate with the through portion 74 and to have a diameter larger than that of the through portion 74, and the bearing 22 can be inserted through the escape portion 75, and in a state where the sensor circuit board 54 is fixed to the stator 7, the bearing 22 overlaps the through portion 74 and the magnetic sensor 77, so that even if there is a bearing 22 having a diameter larger than that of the through portion 74, the rotation shaft 9 can be inserted through the escape portion 75 without any obstacle. Since the through portion 74 does not increase in size, an appropriate detection position of the magnetic sensor 77 can be maintained.

Further, since the relief portion 75 is formed with a radius R larger than the radial distance D from the center of the rotary shaft 9 to the magnetic sensor 77, the bearing 22 having a diameter preferable in terms of long life can be set.

The shape of the elongated hole of the sensor circuit board, the shape and size of the through portion and the escape portion are not limited to the above-described embodiments, and for example, the diameter of the through portion may be appropriately changed such that the escape portion is a square or polygon. The square hole portion may be omitted as long as it does not interfere with the solder terminal. The number and positions of the screw fixing pieces, the positioning pieces, and the protruding portions can be changed according to the insulator, and the positioning pieces can be omitted.

In the above-described embodiment, the relief portion having a diameter larger than that of the bearing is formed so as to communicate with the through portion of the sensor circuit board to avoid interference with the bearing, but as in the sensor circuit board 54A shown in fig. 8, a through hole 90 may be formed concentrically with the center of the circular portion 65, and the circular portion 65 may be formed to have a size of 180 degrees or more around the rotation shaft 9 with a circumferential gap 91 through which the rotation shaft 9 can pass in the radial direction being left, the through hole 90 being circular with a diameter smaller than that of the bearing 22, and the magnetic sensor 77 being arranged around the outer periphery thereof. The gap 91 is formed so as to leave a region where the angle α shown in fig. 8 (a) is 180 degrees or more, and the screw-fixing piece 66 and the extension 70 serving as a fixing portion to the stator 7 are disposed in the region. Here, the relief portion is not provided, and the square hole portion 92 is formed separately from the through hole 90.

In this modification, when assembling brushless motor 4, first, as shown in fig. 8, rotor 8 to which

bearings

21 and 22 and centrifugal fan 82 are attached is inserted from the upper insulator 51 side through stator 7 before sensor circuit board 54A is attached, first of all, with bearing 22 as the former.

Next, as shown in fig. 9, the surface of the sensor circuit board 54A on the magnetic sensor 77 side is directed toward the lower insulator 52, the rotating shaft 9 is inserted through the gap 91 inside the bearing 22, and the sensor circuit board 54A is slid in the radial direction of the gap 91. Then, the rotary shaft 9 is relatively moved toward the through hole 90 side in the gap 91, the sensor circuit board 54A is positioned at the mounting position where the screw fixing piece 66 and the through

holes

67, 71 of the protruding

portions

70, 70 are aligned with the respective screw posts 57, and the

small holes

69, 69 of the

positioning pieces

68, 68 are fitted to the

respective positioning bosses

58, 58.

Then, the screw fixing piece 66 and the

extension portions

70, 70 are fixed to the respective screw posts 57 by the

screws

87, 87 …, and the brushless motor 4 is assembled in the main body case 2 after the assembly is completed. Here, by using the bearing 22 having a diameter larger than that of the through hole 90, the magnetic sensor 77 and the bearing 22 located around the outer periphery of the through hole 90 overlap each other in the axial direction of the rotary shaft 9 as shown in fig. 9 (a).

In this way, in the modification, since the sensor circuit board 54A is formed to have a size of 180 degrees or more around the rotation shaft 9 while leaving the gap 91 in the circumferential direction through which the rotation shaft 9 can pass in the radial direction, even in the bearing 22 having a diameter larger than the diameter of the through hole 90, the rotation shaft 9 can pass through the gap 91 without hindrance. Further, since the screw-fixing piece 66 and the extension 70 fixed to the stator 7 are provided in the area of 180 degrees or more, the sensor circuit board 54A can be firmly fixed to the stator 7 even if the gap 91 is provided.

The angle of the remaining (area) of the sensor circuit board formed by forming the gap may be 180 degrees or more, or may be smaller than the example of fig. 8.

In addition, the present invention is not limited to the hammer drill, and other electric tools such as an electric hammer, an electric drill (driver dril), an electric wrench, and a circular saw can be used if the electric tool uses a brushless motor as a driving source. Or an AC machine that does not use a battery pack.

However, the above-described aspect can also be understood as an invention of a brushless motor not limited to the following electric power tool.

1. A brushless motor (4) having a stator (7), a rotor (8), and a sensor circuit board (54, 54A), wherein the rotor (8) has a rotation shaft (9); the sensor circuit boards (54, 54A) are fixed to the stator (7), are penetrated by the rotating shaft (9), and are provided with a rotation detection element (77) for detecting the rotation of the rotor (8),

the brushless motor (4) is characterized in that,

comprises a bearing (22) mounted on a rotating shaft (9),

a bearing (22) of the rotating shaft (9) and a rotation detection element (77) of the sensor circuit board (54, 54A) overlap in the axial direction of the rotating shaft (9).

2. A brushless motor (4) having a stator (7), a rotor (8), and a sensor circuit board (54, 54A), wherein the rotor (8) has a rotation shaft (9); the sensor circuit boards (54, 54A) are fixed to the stator (7), are penetrated by the rotating shaft (9), and are provided with a rotation detection element (77) for detecting the rotation of the rotor (8),

the brushless motor (4) is characterized in that,

comprises a bearing (22) mounted on a rotating shaft (9),

the sensor circuit board (54, 54A) has a hole (75), and the hole (75) is formed with a radius (R) larger than the distance (D) from the center (O) of the rotating shaft (9) to the rotation detection element (77).

3. A brushless motor (4) having a stator (7), a rotor (8), and a sensor circuit board (54A), wherein the rotor (8) has a rotation shaft (9); the sensor circuit board (54A) is fixed to the stator (7), is penetrated by the rotating shaft (9), and is mounted with a rotation detection element (77) for detecting the rotation of the rotor (8),

the brushless motor (4) is characterized in that,

comprises a bearing (22) mounted on a rotating shaft (9),

the sensor circuit board (54A) is formed in such a size that the angle around the rotating shaft (9) reaches 180 degrees or more while at least a circumferential gap (91) through which the rotating shaft (9) can pass in the radial direction is left, and fixing portions (66, 70) for fixing to the stator (7) are provided in the region of 180 degrees or more.

The following invention of the method of assembling the brushless motor can be understood.

1. A method of assembling a brushless motor (4) in which a rotor (8) having a rotating shaft (9) and a bearing (22) thereof is assembled to a stator (7), a sensor circuit board (54) penetrated by the rotating shaft (9) and mounted with a rotation detection element (77) for detecting rotation of the rotor (8) is assembled to the stator (7),

the method of assembling the brushless motor (4) is characterized in that,

the sensor circuit board (54) has a through hole (74) and a relief hole (75), wherein the through hole (74) is penetrated by the rotating shaft (9), and a rotation detection element (77) is arranged outside the through hole; the avoidance hole (75) is communicated with the through hole (74) and can be penetrated by the bearing (22),

after the rotor (8) is assembled on the stator (7), the bearing (22) and the rotating shaft (9) penetrate through the avoiding hole (75) of the sensor circuit board (54), then the sensor circuit board (54) is positioned at the assembling position of the rotating shaft (9) in the through hole (74), and then the sensor circuit board (54) is assembled on the stator (7).

2. A method of assembling a brushless motor (4) in which a rotor (8) having a rotating shaft (9) and a bearing (22) thereof is assembled to a stator (7), a sensor circuit board (54) penetrated by the rotating shaft (9) and mounted with a rotation detection element (77) for detecting rotation of the rotor (8) is assembled to the stator (7),

the method of assembling the brushless motor (4) is characterized in that,

the sensor circuit board (54) has a hole portion (75), the hole portion (75) is formed with a radius (R) larger than a distance (D) from a center (O) of the rotation shaft (9) to the rotation detection element (77),

after the rotor (8) is assembled to the stator (7), the bearing (22) and the rotating shaft (9) are inserted into the hole (75) of the sensor circuit board (54), the sensor circuit board (54) is positioned at an assembly position where the rotating shaft (9) is positioned in the through hole (74), and the sensor circuit board (54) is assembled to the stator (7).

3. A method of assembling a brushless motor (4) in which a rotor (8) having a rotating shaft (9) and a bearing (22) thereof is assembled to a stator (7), a sensor circuit board (54A) penetrated by the rotating shaft (9) and mounted with a rotation detection element (77) for detecting rotation of the rotor (8) is assembled to the stator (7),

the method of assembling the brushless motor (4) is characterized in that,

the sensor circuit board (54A) is formed in such a size that a circumferential gap (91) through which the rotating shaft (9) can pass in the radial direction is maintained and the angle around the rotating shaft (9) reaches 180 degrees or more,

after the rotor (8) is assembled to the stator (7), the sensor circuit board (54A) is assembled to the stator (7) by positioning the sensor circuit board (54A) at an assembly position where the rotary shaft (9) is positioned in the through hole (90) after the rotary shaft (9) is inserted through the gap (91) of the sensor circuit board (54A).

Claims

1. An electric tool is characterized in that the electric tool is provided with a power supply unit,

having a housing, a brushless motor and a bearing, wherein,

the brushless motor has: a stator; a rotor having a rotation axis; and a sensor circuit board that is fixed to the stator, is penetrated by the rotating shaft, and has a rotation detection element mounted thereon for detecting rotation of the rotor;

the bearing is held by the housing and supports the rotary shaft,

the bearing of the rotary shaft and the rotation detecting element of the sensor circuit board overlap in an axial direction of the rotary shaft,

the sensor circuit board is provided with a through hole and an avoidance hole, wherein the through hole is penetrated by the rotating shaft, and the rotating detection element is arranged around the periphery of the through hole; the avoiding hole is communicated with the through hole and is formed into a diameter larger than the diameter of the through hole, the bearing can penetrate through the avoiding hole, and the bearing is overlapped with the through hole and the rotation detection element when the sensor circuit board is fixed to the stator in a fixed state.

2. An electric tool is characterized in that the electric tool is provided with a power supply unit,

having a housing, a brushless motor and a bearing, wherein,

the bearing is held by the housing and supports the rotary shaft,

the sensor circuit board is provided with a through hole and an avoidance hole, wherein the through hole is penetrated by the rotating shaft, and the rotating detection element is arranged around the periphery of the through hole; the avoidance hole is communicated with the through hole and is formed to have a diameter larger than that of the through hole, the bearing can penetrate through the avoidance hole,

the avoidance hole is formed at a radius larger than a distance from the center of the rotation axis to the rotation detecting element.